One subassembly of the power train of a fork lift truck includes a differential, two jack shafts a wheel drive assembly on each jack shaft, and means for supporting these components with respect to the frame of the lift truck. This power train subassembly also includes a braking system for each wheel which employs either shoe brakes or disc brakes.
Disc brakes have heretofore not received wide utilization on fork lift trucks because of the problems of space and lubrication. A lift truck has a very small, central hub area which greatly limits the size, the type of brake and the means for actuating the brake. Lubrication for wet disc brakes is a problem if direct lubrication is required from the differential. An open tube is necessary and direct fluid access must be provided between the differential and the brakes. If separate lubrication is required, then the differential and the jack shafts must be sealed.
Further problems with disc brakes include providing mechanical actuation when the brakes are used for parking and hydraulic actuation when the brakes are used as service brakes. In addition, the disc brakes and the actuating system must permit both easy removal of the differential and also support for the differential during operation.
Prior work in the field of mounting lift truck differentials includes U.S. Pat. No. 4,100,986 entitled "Split Pillow Block For Mounting A Differential" by W. Shipitalo, issued on July 18, 1978; and U.S. Pat. No. 4,100,988 entitled "Vehicle Including Differential Mounting" issued July 18, 1978 to H. Hildebrecht.
Prior designs for actuating lift truck disc brakes include U.S. Pat. No. 3,048,241 entitled "Disc Brake Actuating And Adjusting Mechanism" by O. K. Kelley et al., issued on Aug. 7, 1962; U.S. Pat. No. 3,638,763 entitled "Mechanical Actuating Mechanism For Disc Brake" by Bernard Laverdant, issued on Feb. 1, 1972; U.S. Pat. No. 3,674,118 entitled "Full Disc Brake With Rotating Brake Discs" by Hermann Klaue, issued on July 4, 1972, and U.S. Pat. No. 3,701,400 entitled "Parking Actuator For Disc Brake" by Richard T. Burnett et al., issued on Oct. 31, 1972.
The present invention is directed to overcoming one or more of the problems as set forth above.